Process variable transmitters are used to sense process variables and provide electrical outputs that represent the magnitudes of the process variables. As electronic and sensor components in process variable transmitters are increasingly miniaturized, and more functions are added to the transmitters, the circuitry inside the transmitter becomes packed very densely, leading to new power management, noise and interference problems internal to the transmitter.
There is a problem with noise affecting low level sensor circuitry in two-wire HART transmitters that also include a controller area network (CAN) transceiver line. There is a need to provide better protection from noise in sensor circuitry in miniature two-wire process variable transmitters that include a CAN transceiver line.
There is also a problem with meeting the energization needs of the CAN circuitry and other transmitter circuitry from the loop energization which is mismatched to the energization needs.
Transmitters are needed that overcomes these problems. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.